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Squat research for inland ships

AuthorsWytze de Boer
Conference/JournalMARIN Report 133
DateApr 8, 2022
Reading time6 minutes
Recent periods of low water highlight the importance of understanding the squat (sinkage & trim due to ship speed) of inland ships for a single ship in a fairway, and for ships in traffic situations. This is addressed in a joint research project initiated by the Directorate-General for Public Works and Water Management (Rijkswaterstaat) and MARIN.


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There are several empirical formulas to estimate the squat of a ship. Previously, MARIN has assessed methods for inland ships in confined waters. The interaction between ships also has an impact. In the figure, speed and sinkage at the bow were measured on a loaded 110m*11.45m inland ship (draught 3.45m) when it encountered a tanker of 135m*17.6m in the Amsterdam-Rhine Canal (depth of 6m). The tanker had a draught of 3.1m and speed of 13 km/hr. During the encounter, the maximum sinkage increased by more than 100% with respect to the single ship, to approximately 0.45m.
Squat research for inland ships
Squat Overtaking
Results of a ReFRESCO CFD calculation of the dynamic sinkage and trim of two identical 110m * 11.40m inland ships. One ship sailing at 14 km/hr overtaking the other one at 12 km/hr. Draught of both ships 3.5m, water depth 4.55m